I have a comfortmaker A/C unit that is 7 years old when the stat calls for air all I get is a constant humming noise from the outside unit. Also when it is humming it is getting hot I have been able to start the fan by spinning it and tapping the the fan motor however that is getting harder to do. After reading some postings today I removed the capacitor today and had it tested at a HVAC shop and they said it tested 47 and it was labeled as 50 so it was fine. I then removed the blower motor took it apart to see if there was noticeable problems. I did not see anything so I put it back together and it fired up with no humming. when it satisfied the stat it shut off and when it called for air again the humming started but the fan did start after a delay. I also should note that I believe the fan motor says RPM 840/2spd does that mean 2 speed fan motor and what would be my next move.

replace the motor
be sure to get a new capacitor that matches the motor

take the old motor with you

wmpeoop probably is giving you the right answer but there is one thing I would do first since they are so cheap and that is to replace the capacitor. Then if it does not run ir might be time to change the motor.

One question, does the motor run O. K. after you get it started?

yes it does cool when I hand start the the fan motor. However I do not think it ever changes speeds like it should. My other A/C makes a definite change of speed to stage 2.